/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* deleteDuplicates(ListNode* head) {
        ListNode* cur=head;
        if (!head) return head;
        while(cur->next){
            ListNode* p=cur->next;
            if((cur->val)==(p->val)){
                cur->next=p->next;
            }
            else{
                cur=cur->next;
            }
            
        }
    return head;
    }
};